Date: Tue, 24 Apr 2018 14:17:07 +0300 From: Mikhail Zakharov <zmey20000@yahoo.com> To: karli@inparadise.se Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org>, Mike Tancsa <mike@sentex.net> Subject: Re: ctl_isc_lun_sync: Received conflicting HA LUN Message-ID: <C3858DFD-7263-4400-A654-B2170D67FF9D@yahoo.com> In-Reply-To: <1524567621.9560.65.camel@inparadise.se> References: <4cb4aa83-bd49-0c20-4e41-c11c682b0570@sentex.net> <F908B78A-DD9B-4204-BA1E-24CE38059ACF@yahoo.com> <1e1e7cd5-0797-c168-fbce-a36edc6a432e@sentex.net> <1524550160.1130.6.camel@inparadise.se> <615DFFBB-239A-4350-B961-FD10D0C9A8DD@yahoo.com> <1524567621.9560.65.camel@inparadise.se>
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I don=E2=80=99t think, adding a third node will add accuracy to BQ, and ther= e is no network connection involved with BQ usage. Also if both nodes have s= toped updating stamps, the system is dead. But the third node may be configu= red to handle all other issues related to any interconnections and death of B= Q itself :) WBR, Mike > 24 =D0=B0=D0=BF=D1=80. 2018 =D0=B3., =D0=B2 14:00, Karli Sj=C3=B6berg <kar= li@inparadise.se> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0): >=20 >> On Tue, 2018-04-24 at 12:32 +0300, Mikhail Zakharov wrote: >> Hi Karli, >>=20 >> Thank you, I=E2=80=99m just exploring the storage abilities of my preferr= ed >> OS - FreeBSD.=20 >>=20 >> Three nodes are preferable to choose the quorum for sure, but my idea >> was not to establish contacts between nodes. Instead of it, BQ uses a >> small partition for the =E2=80=9Cquorum=E2=80=9D on the same space where d= ata volume >> is located.=20 >=20 > Yes, of course. But there=C2=B4s nothing you from having three nodes > connected to the same partition and being able to make more accurate > choices on when to take over? >=20 > If one node stops updating stamps, take over. If two nodes stops > updating, then the problem is likely network-related and _must not_ > take over to avoid split brain. Something like that? >=20 > /K >=20 >> And if a node looses access to the quorum it means, it looses access >> to the data volume too. Now, BQ runs on both nodes and both BQ >> instances write stamps to the quorum partition. If for any reason BQ >> on one node detects, the other node stops updating it=E2=80=99s stamps, i= t >> performs failover procedure. It=E2=80=99s quite a questionable, rude way,= I >> can agree, and that=E2=80=99s why I always write a warning to use the Bea= ST >> for testing only purposes.=20 >>=20 >> Best regards, >> Mike >>=20 >>> 24 =D0=B0=D0=BF=D1=80. 2018 =D0=B3., =D0=B2 9:09, Karli Sj=C3=B6berg <ka= rli@inparadise.se> >>> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0): >>>=20 >>>>> On Mon, 2018-04-23 at 13:11 -0400, Mike Tancsa wrote: >>>>> On 4/23/2018 12:59 PM, Mikhail Zakharov wrote: >>>>>=20 >>>>> Hello Mike, >>>>>=20 >>>>> Thank you for your interest to my paper. I appreciate it very >>>>> much! >>>>> Your error may be a consequence of the initial HA >>>>> misconfiguration. >>>>> What is in your /boot/loader.conf? Although the described >>>>> config is >>>>> quite simple, I can recheck the instruction in my paper in a >>>>> couple >>>>> of weeks only, unfortunately I=E2=80=99m on vacation right now. >>>=20 >>> [snip] >>>=20 >>> I read your articles on CTL HA, BQ and BeaST, and just wanted to >>> say >>> they are amazing, good job! >>>=20 >>> One thing I=C2=B4m wondering about though is if you can claim HA with >>> just >>> two nodes, usually you need at least three, where the third is a >>> tie- >>> breaker. Otherwise with your current setup, both systems may loose >>> contact with each other while both still being powered on, leading >>> to >>> potential split brain situations. What are your thoughts about >>> that? >>>=20 >>> /K >>=20
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